Long‐Lived Photoluminescence in Amorphous Si–O–C(–H) Ceramics Derived from Polysiloxanes

Abstract

The decarbonization process for silicone resin particles in a hydrogen gas flow and the properties of resulting Si-O-C(-H) ceramics were investigated in terms of mass loss, specific surface areas, and photoluminescence (PL) spectra. In particular, PL spectra of Si-O-C(-H) ceramics decarbonized in a hydrogen gas flow at 800°C and 1100°C were investigated in detail using pulsed laser excitation. The powder decarbonized at 800°C (SiO 1.68 C 0.48 H 1.66 ) exhibited short-lived PL with a peak at 410 nm that decayed within a time range of 10-60 ns. After evacuation of the system down to 1 Pa, long-lived PL decaying within a time range of 1.0-4.0 s appeared around 560 nm, in addition to the short-lived PL. On the other hand, the powder decarbonized at 1100°C (SiO 1.54 C 0.26 H 0.12 ) exhibited yellowwhite PL with a peak at 520-530 nm. Time-resolved analysis revealed that the broad emission consisted of both short-lived PL (peak at 500 nm) and long-lived PL (peak at 580 nm).

Investigation of photoluminescence of Si−O−C(−H) ceramics at an early stage of decarbonization by using high energy excitation

“…[10][11][12] Absolute carbon content in these ceramics was reduced to 70-75% of that obtained in an Ar atmosphere. At the same time, the hydrogen content was 2-4 times greater.…”

“…In the previous study, which was made by using a pulsed N 2 laser (337 nm, 3.68 eV) as an excitation light source, this "blue" PL band was observed to show asymmetric feature having a tail at a low energy region. 11 On the other hand, the excitation on high energy region reveals the symmetric feature of the "blue" PL band.…”

“…Blue emission having a peak at 410-420 nm and a life time of 10-60 ns is dominantly observed in the samples decarbonized at 800-900 • C. At decarbonization temperatures of 1000-1300 • C, the ceramics exhibited white broad emission, which consisted of short-lived cyan emission (peak at 490-500 nm) and long-lived yellow emission (peak at 560-580 nm). 11,13 In this article, we pay special attention to a pyrolysis temperature range at 750-850 • C, because a large mass loss of the polysiloxane particles substantially occurs and the blue emission having a peak at 410-420 nm becomes apparent in this temperature range. Detailed monitoring of mass loss, specific surface area and FTIR spectra may give clues on origin of the blue emission.…”

Effects of carbon addition on the electrical properties of bulk silicon-oxycarbide ceramics

“…Polymer-derived ceramics (PDCs) based on Si-O-C have attracted much attention [1,2], especially for potential applications in sensors [3,4], anode materials for Li-ion rechargeable batteries [5][6][7], phosphors in LED systems [8][9][10], immobilization of irradiated graphite waste [11], micro-parts and patterns in hightemperature microelectromechanical systems (MEMS) [12][13][14], porous ceramics for thermal insulators [15,16], water-and gastreatment membranes [17], precursors for SiC powders [18], cost-effective fibers for structural applications [19], and coatings for metal parts [20], due to their attractive mechanical, thermal, creep, and oxidation resistance and chemical properties compared to amorphous SiO 2 [21][22][23][24][25][26][27][28][29]. Although some applications of SiOC ceramics, such as MEMS, Li-ion batteries, pressure sensors, heaters, and sealants, require control of electrical resistivity, data on electrical properties of SiOC ceramics are quite limited.…”

Synthesis and characterization of luminescent properties of ceramics derived from polysilylcarbodiimides

“…On the other hand, there are two possible reasons for the PL emission at the shorter wavelengths: (i) some defects (Si, C or N dangling bond 9),10),18),30),31) ) formed by decomposition or elimination of the trimethylsilyl end groups, and (ii) structure defects of SiOSi formed by accidently contaminated oxygen. 32), 33) In the spectrum of 970°C-heat treated SDC, the dominant PL excitation peak was observed at 366 nm, and the related PL emission peak was detected at 395 nm despite the different excitation wavelengths ( ex. = 366 and 288 nm).…”